Composite sports article

ABSTRACT

The present invention relates to a composite sports article. The composite sports article includes: a first component and a second component which was produced by means of an additive manufacturing technique. The first component and the second component are bonded to each other by a first bonding agent and there is a form-fitted bond between the first bonding agent and the second component and/or the first component and the second component are bonded to each other in a form-fitted manner via a first bonding agent.

TECHNICAL FIELD

The present invention relates to an improved method for bondingcomponents, for a composite sports article, that cannot be easily bondedadhesively.

PRIOR ART

Additive manufacturing techniques, commonly also referred to as 3Dprinting, used to be limited to so-called “rapid prototyping”. This ismainly due to the fact that the speed of production and the materialsavailable for additive manufacturing techniques used to limit theirapplication to the production of prototypes rather than finishedproducts. Owing to advances in additive manufacturing techniques,particularly as regards the speed of production, such techniques are nowstarting to become mature enough for use in a production environment.

Sports articles such as apparel, footwear, or accessories such asgloves, shin guards, etc. are subject to high demands regarding materialproperties. For example, a shoe needs to provide a high level ofprotection and support for a foot in some areas yet be flexible andprovide cushioning in other areas. Moreover, the human anatomy variessignificantly from one athlete to another. Traditional manufacturingtechniques, such as injection molding, do not allow for customizationthat goes beyond predetermined sizes, such as for example large (L),medium (M), or small (S) for apparel or sizes 46, 47, or 48 for shoes inthe European system.

Additive manufacturing techniques allow for a level of customizationthat would be neither technically nor economically feasible usingexisting manufacturing methods. Thus, additive manufacturing techniquespromise an unprecedented level of customization for sports articles. Forexample, the shoe may be customized for an athlete not only in terms ofits size and shape, but also in terms of its functionality, such as thelevel of cushioning, the level of support, etc.

Most sports articles are composite articles consisting of more than onecomponent. For example, a shoe typically requires at least an upper anda sole element. The upper may be weft-knitted, warp-knitted, woven,non-woven, etc., while the sole element can be produced by means ofadditive manufacturing techniques.

However, an existing challenge in additive manufacturing techniques isthat some of the materials suitable for additive manufacturing may havepoor adhesive properties. For example, the materials suitable foradditive manufacturing techniques typically comprise a plasticizer thatleads to poor adhesion in combination with a wide range of bondingagents. Moreover, many materials that are suitable for additivemanufacturing techniques are not thermoplastic and therefore cannot bethermally welded. Therefore, using existing methods, it is not possibleto form a sports article as a composite article comprising a firstcomponent that is securely bonded to a second component, if the secondcomponent is produced by means of additive manufacturing techniques.

It is therefore an object underlying the present invention to provide acomposite sports article and method for the production thereof thatallows for individual customization but whose components are alsosecurely bonded to each other in order to withstand the stresses ofregular usage during physical activity.

For producing shoes individually adapted to the needs of the respectiveuser, it is for example known from DE 10 2005 023 473 A1 to draw onmethods of rapid prototyping, such as additive manufacturing methods(e.g. layer manufacturing methods), for manufacturing an upper and/orsole.

It is, in turn, known from DE 10 2015 206 900 A1 to first manufacturethe upper and the sole separately and to only bond these to each otherin a subsequent step of manufacturing. Such an approach has advantagesregarding manufacturing engineering. However, the bond between the upperand the sole is a potential weakness of the shoe, as shearing off canoccur in the area of a bonding interface between the upper and the sole.It is conceivable to improve the quality of the bond between the upperand the sole by inserting an adhesive compound consisting of a hot meltlayer and a TPU (thermoplastic polyurethane) layer. However, thisapproach would be technically complex and would increase the number ofmaterials required. Moreover, the TPU layer would have to be formed in aseparate upstream method step.

Thus, it is a further technical object underlying the present inventionto create a shoe exhibiting a high bonding strength between the upperand sole, which are first manufactured separately.

SUMMARY OF THE INVENTION

This object is achieved by the teachings of the independent claims. Theinvention particularly concerns a composite sports article, comprising:a first component; a second component, which was produced by means of anadditive manufacturing technique; wherein the first component and thesecond component are bonded to each other by a first bonding agent andwherein there is a form-fitted bond between the first bonding agent andthe second component; and/or wherein the first component and the secondcomponent are bonded to each other in a form-fitted manner via a firstbonding agent.

The term “additive manufacturing techniques” is to be understood in theconventional manner. This means that additive manufacturing techniquesrefers to all techniques applying an additive shaping principle andthereby building physical 3D geometries by successive addition ofmaterial. Additive manufacturing techniques include 3D printing andtechniques sometimes referred to as “rapid prototyping”. In particular,additive manufacturing techniques comprise techniques such as lasersintering, direct metal laser sintering, selective laser melting, fuseddeposition modeling FDM®, fused filament manufacturing, andstereolithography. Any additive manufacturing technique is suitable forthe present invention.

A bonding agent is any compound or composition that has any level ofadhesion on the first component and/or the second component. It is to benoted that this level of adhesion may be very low. Especially on thesecond component, the chemical bond of the bonding agent may be veryweak. In general, thermoplastic materials, in particular hot melts,thermoplastic polyurethane, a polyamide (PA) or a polyether block amide(PEBA), are suitable as bonding agents.

According to the invention, there can be a form-fitted bond between thebonding agent and the second component, meaning that the bond betweenthe first component and the second component is only form-fittedindirectly via the bonding agent. However, it is also possible that thebond between the first component and the second component is directlyform-fitted, with the bond still using a first bonding agent, forexample to generate a basic adhesion to hold the first and the secondcomponent in the form-fitted bond. The composite sports article inaccordance with the invention comprises a strong bond between the firstcomponent and the second component, even if the bonding agent does notadhere strongly to the second component. The bond is especially strongagainst lateral forces, such as shear forces.

The composite sports article may be an article of footwear, an articleof apparel, or a sports accessory. The sports accessory in this contextis any item used or worn during an athletic activity. A shin guard,gloves, or a sports racket are examples of sports accessories. Anarticle of footwear, an article of apparel, or a sports accessory issubject to high forces, strains and torques during physical activity.Therefore, it is particularly important that the bond between the firstcomponent and the second component is strong.

The composite sports article may be a shoe, the first component may be apart of a shoe upper and the second component may be a part of a sole.The term “upper” in the context of the present invention refers to a“shoe upper” unless anything else follows from the context. A shoe inthe present context is any type of shoe, for example a soccer boot, ahiking boot, a running shoe, or a sandal. The present invention isgreatly beneficial for a shoe, which needs to be strong and durable asit is exposed to the whole weight of the athlete. For example, a weakbond between the shoe upper and the sole may increase the risk of theupper tearing off the sole during physical activity. The shoe also needsto provide the right level of support, for example around the ankle, yetit has to be flexible, for example in an instep region and provide theright level of cushioning, for example in a heel region. Thus, it isadvantageous to form the shoe as a composite article. A sole at leastpartly formed by means of additive manufacturing techniques allows forthe right level of cushioning for each part of the foot and may beindividually customized for the athlete. For example, the heel regionmay be engineered to provide a high level of cushioning while the toeregion may be engineered to be firmer than the heel region. The presentinvention therefore provides a composite shoe with a preferred level offit and ideal functional properties that is at the same time durable dueto the strong bond between the shoe upper and the sole.

The composite sports article may be a shoe and the first component maybe a bottom side of the shoe upper and the second component may be atopside of the sole.

The shoe upper may be a textile shoe upper. For example, the shoe uppermay be at least partially weft-knitted and/or partially warp-knitted.Such a shoe upper is particularly flexible and comfortable to wear. Theshoe upper may also be at least partially woven or non-woven. Moreover,the shoe upper may comprise at least one reinforcement element.

The second component may comprise an activated photopolymer. Here, aphotopolymer is any substance that can be activated, i.e. cured, bylight, wherein activation causes a liquid photopolymer to solidify. AUV-curable resin is an example of a photopolymer. UV is an abbreviationfor ultraviolet. The second component can for example comprise a mixtureof UV-curable resin and polyurethane. In the cured state, this mixtureyields a stiff and durable second component.

By using a photopolymer, it is possible to construct the secondcomponent by stereolithography which allows for the second component tobe built with a particularly high resolution at fast production speeds.

In addition to the activation by light, the photopolymer is preferablyhardened additionally, for example by heating the second component withhot air, conductive heating (heat pressing), infrared radiation, or byany other suitable method. This additional hardening may greatlyincrease the strength of the material, for example as measured by theYoung's modulus of the material. Hardening at ambient temperature isalso possible in principle, however, this would occupy more time.

The second component may comprise a lattice structure comprising aplurality of voids. The voids may be connected to one another to formone large void within a mesh-like structure, or the voids may not beconnected to one another. A lattice structure is preferable for aplurality of applications as it allows for a strong, yet flexible andcushioning structure to be produced at low weight. Moreover, a latticestructure offers good breathability.

The properties of the lattice can be engineered to be anisotropic, forexample the lattice may stretch easily in one direction and less easilyin another direction. Additionally or alternatively, the lattice may beengineered to be dense in a first part of the second component and lessdense in a second part of the second component, hence forming a firmfirst part and a softer, more cushioning second part.

In the second component, at least one first form-fitting element can beprovided. Additive manufacturing techniques allow for a plurality ofpossibilities of providing a first form-fitting element in the secondcomponent. Thus, it is of particular advantage if the second componentcomprises a first form-fitting element. The second component maycomprise a second form-fitting element or any desired number ofform-fitting elements.

The first form-fitting element may be provided on the topside of thesole. If the second component is a topside of a sole of a shoe, it isadvantageous that the first form-fitting element is provided on thetopside of the sole in order to allow for a directly or indirectlyform-fitted bond with a shoe upper.

For practical purposes, form-fitting elements for forming theform-fitted bond between the upper and the sole are for example providedon the topside of the sole in a knob-like shape. For example, whenenclosed by the hot melt layer, they can result in the form-fittedbonds. The specific geometric shape of the individual form-fittingelements can vary in a wide range in this respect.

The first form-fitting element can be provided on a midsole of amulti-layered sole such that it faces the shoe upper. It can be ofadvantage to provide ideal cushioning properties via a midsole. In thiscase, the midsole is advantageously bonded to the shoe upper in adirectly or indirectly form-fitted manner.

In an advantageous manner, at least one midsole in a multi-layered solearrangement can be produced at least partly by means of an additivemanufacturing method. By means of additive manufacturing, parts of thesole itself as well as its form-fitting elements can be producedintegrally from one material in one operation. Hence, the individualoperations and the materials used are kept to a minimum. At the sametime, the advantages of additive shoe manufacturing (such ascustomization of the shoe's form and size in the sole region to theuser's needs) can be maintained. In this regard, it is not necessary toproduce an entire setup of a multi-layered sole additively. Rather, itis sufficient—if required—to additively produce in particular an upperregion (i.e. the region of the sole where the form-fitting elements areprovided facing the hot melt layer). The further regions of the sole canalso be produced by means of conventional manufacturing techniques. Inparticular if the sole has a multi-layered structure, it can beadvantageous to merely additively produce the midsole facing thementioned exemplary hot melt layer, i.e. a bonding agent, while theoutsole is for example manufactured conventionally. Conventionalmanufacturing can for example be carried out using an injection moldingmethod and thus be fast and cost-effective. Hence, the advantages ofboth methods can be combined.

The midsole can further comprise a second form-fitting element whichfaces an outsole of the multi-layered sole and which is bonded to theoutsole via a second bonding agent or in direct engagement in aform-fitted manner. Hence, it is possible to also provide a directly orindirectly form-fitted bond between the outsole and the midsole toimprove the resilience of the bond between the outsole and the midsoleparticularly against lateral forces, such as shear forces.

If the midsole is profiled for form fitting on its two surfaces, themidsole can be bonded to both the shoe upper and the outsole viaboth-sided bonding agents, such as hot melt layers. However, for thebond with a thermoplastic outsole, the lower form-fitting elements ofthe midsole can also directly (i.e. without an additional hot meltlayer) engage downwards in the outsole. Besides the form-fitted bondbetween the bonding agent, e.g. hot melt layer, and the topside of thesole described above, there can also be an additional form-fitted bondbetween the bonding agent, e.g. hot melt layer, and the bottom side ofthe upper. In this manner, the bonding strength between the upper andthe sole can be further increased. This additional form-fitted bond canbe based on form-fitting elements provided on the bottom side of theupper. The geometrical form of these form-fitting elements may, in turn,correspond to the forms mentioned above with respect to the form-fittingelements on the topside of the sole. However, as shoe uppers typicallyconsist of textile fabric, it is also possible to dispense with theformation of concrete form-fitting elements on the bottom side of theupper and to provide a form-fitted bond between the textile fabric andthe bonding agent, e.g. the hot melt layer.

The first and/or the second form-fitting element can be provided as apunctiform indentation and/or as a punctiform protrusion.

The first and/or the second form-fitting element can be provided as achannel-shaped indentation and/or as a surfacing bar. A channel-shapedindentation can be provided such that a channel extends along a surfaceof the second component, for example as a groove in a surface of thesecond component. A channel-shaped indentation can, however, also beprovided such that a longitudinal direction of the channel extends intoa surface of the second component. A surfacing bar can be provided suchthat a longitudinal direction of the surfacing bar extends along asurface of the second component.

For example, punctiform indentations or protrusions (i.e.“one-dimensional form-fitting elements”) as well as elongated elements(e.g. channels and/or bars) or complex elements provided on the bondinglevel between sole and hot melt layer (i.e. “two-dimensionalform-fitting elements”) are possible; preferably, these form-fittingelements lead to the form fitting owing to undercuts in a directionparallel to the bonding level between the upper and the sole.

The composite sports article may further comprise a first channel with afirst opening, of first width, arranged in a first surface of the secondcomponent, wherein the first channel is at least partially filled withthe first bonding agent; wherein the first component is bonded to thesecond component at a bonding interface located adjacent to the firstsurface of the second component, and wherein the bonding interfacecomprises the first bonding agent.

The term “width” as used in the present application is to be understoodin the broadest sense of the word “extent”. In particular, the width canbe measured at any angular orientation in a cross-sectional plane withinthe channel, wherein the cross-sectional plane is preferablyperpendicular to a longitudinal direction of the channel. Thecross-section of the channel may be circular, elliptical, rectangular,or may have any other geometry including an irregular geometry.

The first opening may have any regular, for example circular,elliptical, or rectangular, or irregular shape, on the first surface. Incase of a non-circular shape, the first width is the greatest distancebetween two opposite sides of the first opening on the first surface ofthe second component. For example, for an elliptical opening, the firstwidth is defined as the full length of the major axis of this ellipticalopening. The first opening may be located adjacent to the bondinginterface.

Due to the first channel that is at least partially filled with thebonding agent, the bond is strong especially against lateral forces,such as shear forces. Lateral forces are forces that are substantiallyat a 90 degree angle to a longitudinal direction of the first channel.Since the total area available for a chemical bond is increased due tothe presence of the first channel, the bond is also improved againstforces along a longitudinal direction of the first channel.

The bonding interface may be located in a rim portion of the midsole. Itis advantageous for the bonding interface to be located in a rim portionof the midsole, as this allows for the upper to be bonded to the midsoleall the way around the midsole, creating a strong bond, yet it may notbe necessary to bond the upper to the midsole at the center of themidsole, i.e. outside of the rim portion. This reduces the amount ofbonding agent required, therefore reducing the weight of the article offootwear. Moreover, the breathability of the shoe is improved by thisarrangement.

The second component may comprise a second surface, wherein the secondsurface comprises a second opening, of a second width, to the firstchannel. The curing, or hardening, of the bonding agent is improved by asecond opening of the first channel.

The second opening may have any regular, for example circular, orirregular shape, on the second surface. In case of a non-circular shape,the second width is the greatest distance between two opposite sides ofthe second opening on the second surface of the second component. Forexample, for an elliptical opening, the second width is defined as thefull length of the major axis of this elliptical opening.

The bonding agent may spill out of the second opening of the firstchannel on the second surface of the second component thus forming adroplet of a third width, wherein the third width is greater than thesecond width. The droplet may have any regular, for example circular, orirregular shape. In case of a non-circular shape, the third width is thegreatest distance between two opposite sides of the droplet on thesecond surface of the second component. The droplet may, for example,form a “mushroom head”. Therefore, if there were a force directed fromthe second opening of the first channel to the first opening of thefirst channel, along a longitudinal direction of the first channel, thedroplet would generate a mechanical resistance against this force.Hence, the droplet provides a mechanical adhesion between the firstcomponent and the second component. For an improved level of mechanicaladhesion, it is preferable for the third width to be at least 20% largerthan the second width, more preferably the third width is at least 40%larger than the second width.

The first channel may have a fourth width inside the second component;wherein the fourth width may be greater than the first width, and/orwherein the fourth width may be greater than the second width; orwherein the fourth width may be equal to the second width and to thefirst width. It is to be understood that the statements made hereinconcerning the geometric shape and determination of the first widthapply analogously to the second, third, and fourth width. When a widthis determined inside the channel, the width can be measured at anyangular orientation in a cross-sectional plane within the channel,wherein the cross-sectional plane is preferably perpendicular to alongitudinal direction of the channel. The cross-section of the channelmay be circular, elliptical, rectangular, or may have any other geometryincluding an irregular geometry.

In other words, the fourth width may be greater than the first width, orthe fourth width may be greater than the second width, or the fourthwidth may be greater than the first and the second width. If the fourthwidth is greater than the first width, there will be a mechanicalresistance preventing the bonding agent from sliding towards the firstopening of the first width under the influence of force towards thefirst opening, thereby improving the strength of the bond between thefirst component and the second component. If the fourth width is greaterthan the second width, there will be a mechanical resistance preventingthe bonding agent from sliding towards the second opening of the secondwidth under the influence of force towards the second opening, therebyimproving the strength of the bond between the first component and thesecond component. If the fourth width is greater than the first andsecond width, there will be a mechanical resistance preventing thebonding agent from sliding towards the first opening of the first widthand the second opening of the second width under the influence of aforce, thereby improving the strength of the bond between the firstcomponent and the second component.

Alternatively, the fourth width may be equal to the second width and thefirst width. This arrangement allows for the best flow of the liquidbonding agent into the first channel and possibly through the firstchannel. This arrangement may therefore be particularly suitable for asecond component for which a long first channel is required.

At least one of the first, second, third, or fourth width may be between0.3 mm and 3 mm. The inventors have found that if the first, second, or,if applicable, fourth width is too small, it is difficult to incorporatethe bonding agent into the first channel and that if the first, second,or, if applicable, fourth width is too large, the bond is not strongenough. The inventors have found that a preferred range of the first,second, or, if applicable, fourth width is therefore between 0.3 mm and3 mm, more preferably, between 0.5 mm and 2 mm. The third width isdetermined by the second width and the amount of bonding agent pushedthrough the first channel.

A longitudinal axis of the first channel may be at an angle of between80 and 110 degrees to the first surface and/or the second surface of thesecond component. The inventors have found that in this arrangement, itis particularly easy to incorporate the bonding agent into the firstchannel.

In case that the first surface and/or the second surface is not flat,the angle between the longitudinal axis of the first channel is theangle between a tangential direction to the surface immediately adjacentto the first opening (in case of the first surface) or the secondopening (in case of the second surface).

A longitudinal axis of the first channel may be at an angle of between35 and 55 degrees to the first surface and/or the second surface of thesecond component. By arranging the first channel in this orientation,the strength of the bond can be improved for at least two reasons.

Firstly, the length of the first channel and therefore the areaavailable for bonding can be increased, even when the maximum depth ofthe channel is limited, for example by the thickness of the secondcomponent. Here, the depth of the channel is defined as the separationmeasured at a right angle to the first surface between the deepest pointof the channel, which may be at the second opening, and the firstopening.

Secondly, for a force at a right angle to the first surface, thecomponent of the force along a longitudinal direction of the firstchannel, i.e. parallel to the wall of the first channel, that is, thecomponent that needs to overcome the sliding friction of the bondingagent in the first channel, is reduced by an angular decomposition ofthe force. For example, if there is a force F at right angles to thefirst surface pulling the bonding agent towards the first opening and ifa longitudinal axis of the first channel is at an angle of 45° to thefirst surface, the force along the longitudinal axis only amounts toapproximately 71% of F. Thus, it is harder to pull the first componentat right angles to the second component off of the second component;therefore, the bond between the first component and the second componentis stronger.

The first and/or second bonding agent may be a hot melt. Handling of ahot melt releases significantly less volatile organic compounds, such assolvents, than handling of other bonding agents. Moreover, activation ofthe hot melt, by melting, can be easily timed and controlled, thussimplifying and improving the production process.

The holt melt can form a hot melt layer. The hot melt layer may largelycover a bonding interface, or bonding area, between the first componentand the second component. However, it is also possible that the hot meltis only applied point-wise in order to reduce the weight of thecomposite sports article.

The first component may further comprise a protective layer to preventthe first and/or the second bonding agent from entering the firstcomponent. In order to ensure the best possible bond for a given amountof first and/or second bonding agent, it is advantageous to prevent thebonding agent from entering the first component. Therefore, it may bepreferable to use a protective layer, which may have, for example, ahigher melting temperature than the hot melt, if hot melt is containedin the first and/or second bonding agent.

The protective layer may comprise polyurethane, for examplethermoplastic polyurethane, to provide thermal formability. This way, astrong chemical bond may be formed between the protective layer and thebonding agent. For example, the bonding agent may also comprisethermoplastic polyurethane and the bonding agent may comprise acomposition with a lower melting temperature than the meltingtemperature of the composition of the protective layer. The bond betweenthe protective layer and the bonding agent will therefore be strong andbonding is easy to activate. Moreover, it is thus possible to reliablybond even a first component comprising very finely woven textiles to thesecond component.

The second component may further comprise a second channel. The totalstrength of the bond between the first component and the secondcomponent can be increased if there is not only a first channel, butalso a second channel. There may be a plurality of channels. The secondchannel, or each channel of the plurality of channels may have theproperties of the first channel as described herein.

The smallest distance between an outer edge of the first channel and anouter edge of the second channel may be between 0.3 and 3 mm. Theinventors have found that if the smallest distance between an outer edgeof the first channel and an outer edge of the second channel is toolarge, the total strength of the bond is too weak. On the other hand, ifthe smallest distance between the outer edge of the first channel and anouter edge of the second channel is too small, there is a risk of thesecond component tearing. Therefore, the smallest distance between anouter edge of the first channel and an outer edge of the second channelis preferably between 0.3 mm and 3 mm, more preferably between 0.5 mmand 2 mm.

The present invention also concerns a method of producing a compositesports article, comprising: (a) producing a first component; (b)producing a second component by means of an additive manufacturingtechnique, wherein at least one first form-fitting element is providedon the second component; and (c) bonding the first component to thesecond component by a first bonding agent.

The term “additive manufacturing techniques” is to be understood in theconventional manner. This means that additive manufacturing techniquesrefers to all techniques applying an additive shaping principle andthereby building physical 3D geometries by successive addition ofmaterial. Additive manufacturing techniques include 3D printing andtechniques sometimes referred to as “rapid prototyping”. In particular,additive manufacturing techniques comprise techniques such as lasersintering, direct metal laser sintering, selective laser melting, fuseddeposition modeling FDM®, fused filament manufacturing, andstereolithography. Any additive manufacturing technique is suitable forthe present invention. The terms “manufacturing” and “producing” are tobe considered as being synonymous.

Additive manufacturing techniques allow for a plurality of possibilitiesof providing a first form-fitting element in the second component. Thus,it is of particular advantage if the second component comprises a firstform-fitting element. The second component may comprise a secondform-fitting element or any desired number of form-fitting elements.

A bonding agent is any compound or composition that has any level ofadhesion on the first component and/or the second component. It is to benoted that this level of adhesion may be very low. Especially on thesecond component, the chemical bond of the bonding agent may be veryweak. In general, thermoplastic materials, such as hot melts,thermoplastic polyurethane, a polyamide (PA) or a polyether block amide(PEBA), are suitable as bonding agents.

According to the invention, there can be a form-fitted bond between thebonding agent and the second component, meaning that the bond betweenthe first component and the second component is only form-fittedindirectly via the bonding agent. However, it is also possible that thebond between the first component and the second component is directlyform-fitted, with the bond still using a first bonding agent, forexample to generate a basic adhesion to hold the first and the secondcomponent in the form-fitted bond.

The composite sports article in accordance with the invention comprisesa strong bond between the first component and the second component, evenif the bonding agent does not adhere strongly to the second component.The bond is especially strong against lateral forces, such as shearforces.

The composite sports article may be an article of footwear, an articleof apparel, or a sports accessory. The sports accessory in this contextis any item used or worn during an athletic activity. A shin guard,gloves, or a sports racket are examples of sports accessories. Anarticle of footwear, an article of apparel, or a sports accessory issubject to high forces and torques during physical activity. Therefore,it is particularly important that the bond between the first componentand the second component is strong.

The composite sports article may be a shoe, the first component may be apart of a shoe upper and the second component may be a part of a sole.The term “upper” in the context of the present invention refers to a“shoe upper” unless anything else follows from the context. A shoe inthe present context is any type of shoe, for example a soccer boot, ahiking boot, a running shoe, or a sandal. The present invention isgreatly beneficial for a shoe, which needs to be strong and durable asit is exposed to the whole weight of the athlete. For example, a weakbond between the shoe upper and the sole may increase the risk of theupper tearing off the sole during physical activity. The shoe also needsto provide the right level of support, for example around the ankle, yetit has to be flexible, for example in an instep region and provide theright level of cushioning, for example in a heel region. Thus, it is ofadvantage to form the shoe as a composite article. A sole at leastpartly formed by means of additive manufacturing techniques allows forthe right level of cushioning for each part of the foot and may beindividually customized for the athlete. For example, the heel regionmay be engineered to provide a high level of cushioning while the toeregion may be engineered to be firmer than the heel region. The presentinvention therefore provides a composite shoe with a preferred level offit and ideal functional properties that is at the same time durable dueto the strong bond between the shoe upper and the sole.

The composite sports article may be a shoe and the first component maybe a bottom side of the shoe upper and the second component may be atopside of the sole.

The shoe upper may be a textile shoe upper. For example, manufacturingthe shoe upper may comprise weft-knitting and/or warp-knitting. Such ashoe upper is particularly flexible and comfortable to wear. However,the shoe upper may also be at least partially woven or comprisenon-woven parts. Moreover, the shoe upper may comprise at least onereinforcement element.

When manufacturing the shoe, the upper and the sole can first beproduced separately from one another. During the production of the sole,form-fitting elements are provided on its topside. While the upper istypically manufactured by means of methods known from the textileindustry, at least one layer of the sole is preferably produced by meansof an additive manufacturing method. Subsequently, the topside of thesole and the bottom side of the upper are bonded to each other by a hotmelt layer such that it forms a form-fitted bond at least between theupper and the sole.

If, during bonding the topside of the sole to the bottom side of theupper a pressure is applied to the bonding area between the sole and theupper (particularly perpendicular to the bonding area), the flowingaround the form-fitting elements by the hot melt is supported and theformation of the form-fitted bond is facilitated. In this manner, it canparticularly also be facilitated for the hot melt layer to enter thetextile fabric of the upper such that, hence, both a form-fitted bondbetween the hot melt layer and the sole as well as between the hot meltlayer and the upper is generated.

Producing a second component by means of an additive manufacturingtechnique may comprise: providing a photopolymer and selectivelyactivating the photopolymer in order to form the second component.

Here, a photopolymer is any substance that can be activated, i.e. cured,by light, wherein activation causes a liquid photopolymer to solidify. AUV-curable resin is an example of a photopolymer. UV is an abbreviationfor ultraviolet. The second component can for example comprise a mixtureof UV-curable resin and polyurethane. In the cured state, this mixtureyields a stiff and durable second component.

For example, the second component can be constructed bystereolithography which allows for the second component to be built witha particularly high resolution at fast production speeds. Production ofthe second component may comprise projecting ultraviolet light throughan oxygen-permeable window into a reservoir with a photopolymer. Asequence of UV images are projected onto the photopolymer thusselectively solidifying the photopolymer. The partially-constructedsecond component is lifted out of the photopolymer reservoir by a buildplatform. Oxygen may be supplied through the oxygen-permeable window, inorder to prevent an undesired activation of the photopolymer in a regionaround the oxygen-permeable window, the so-called “dead zone”. Thisallows for a sufficient supply of non-activated photopolymer andprevents the partially-constructed second component from sticking to thewindow.

In addition to the activation by light, the photopolymer is preferablyhardened additionally, for example by heating the second component withhot air, conductive heating (heat pressing), infrared radiation, or byany other suitable method. This additional hardening may greatlyincrease the strength of the material, for example as measured by theYoung's modulus of the material. This additional hardening may beperformed before bonding the second component to the first component inorder to prevent damage to the second component during the bondingoperation. Hardening at ambient temperature is also possible inprinciple, however, this would occupy more time.

Producing the second component may comprise the formation of a latticestructure, comprising a plurality of voids, in the second component. Thevoids may be connected to one another to form one large void within amesh-like structure, or the voids may not be connected to one another. Alattice structure is preferable for a plurality of applications as itallows for a strong, yet flexible and cushioning structure to beproduced at low weight. Moreover, a lattice structure offers goodbreathability.

The properties of the lattice can be engineered to be anisotropic, forexample the lattice may stretch easily in one direction and less easilyin another direction. Additionally or alternatively, the lattice may beengineered to be dense in a first part of the second component and lessdense in a second part of the second component, hence forming a firmfirst part and a softer, more cushioning second part.

The first form-fitting element can be provided on a midsole of amulti-layered sole such that it faces the shoe upper. It can be ofadvantage to provide ideal cushioning properties via a midsole. In thiscase, the midsole is advantageously bonded to the shoe upper in adirectly or indirectly form-fitted manner.

The midsole can further comprise a second form-fitting element whichfaces an outsole of the multi-layered sole and which is bonded to theoutsole via a second bonding agent or in direct engagement in aform-fitted manner. Hence, it is possible to also provide a directly orindirectly form-fitted bond between the outsole and the midsole toimprove the resilience of the bond between the outsole and the midsoleparticularly against lateral forces, such as shear forces.

The first and/or the second form-fitting element can be provided as apunctiform indentation and/or as a punctiform protrusion.

The first and/or the second form-fitting element can be provided as achannel-shaped indentation and/or as a surfacing bar. A channel-shapedindentation can be provided such that a channel extends along a surfaceof the second component, for example as a groove in a surface of thesecond component. A channel-shaped indentation can, however, also beprovided such that a longitudinal direction of the channel extends intoa surface of the second component. A surfacing bar can be provided suchthat a longitudinal direction of the surfacing bar extends along asurface of the second component.

Forming the first and/or second form-fitting element may comprise:forming a first channel with a first opening, of a first width, in afirst surface of the second component; and wherein the method ofproducing a composite sports article may further comprise: forming abond between the first component and the second component at a bondinginterface located adjacent to the first surface of the second component,comprising: applying the first bonding agent to the first surface and atleast partially filling the first channel with the first bonding agent.

The term “width” as used in the present application is to be understoodin the broadest sense of the word “extent”. In particular, the width canbe measured at any angular orientation in a cross-sectional plane withinthe channel, wherein the cross-sectional plane is preferablyperpendicular to a longitudinal direction of the channel. Thecross-section of the channel may be circular, elliptical, rectangular,or may have any other geometry including an irregular geometry.

The first opening may have any regular, for example circular,elliptical, or rectangular, or irregular shape, on the first surface. Incase of a non-circular shape, the first width is the greatest distancebetween two opposite sides of the first opening on the first surface ofthe second component. For example, for an elliptical opening, the firstwidth is defined as the full length of the major axis of this ellipticalopening. The first opening may be located adjacent to the bondinginterface.

Due to the first channel that is at least partially filled with thebonding agent, the bond is strong especially against lateral forces,such as shear forces. Lateral forces are forces that are substantiallyat a 90 degree angle to a longitudinal direction of the first channel.Since the total area available for a chemical bond is increased due tothe presence of the first channel, the bond is also improved againstforces along a longitudinal direction of the first channel.

The bonding interface may be located in a rim portion of the midsole. Itis advantageous for the bonding interface to be located in a rim portionof the midsole, as this allows for the upper to be bonded to the midsoleall the way around the midsole, creating a strong bond, yet it may notbe necessary to bond the upper to the midsole at the center of themidsole, i.e. outside of the rim portion. This reduces the amount ofbonding agent required, therefore reducing the weight of the article offootwear. Moreover, the breathability of the shoe is improved by thisarrangement.

The second component may comprise a second surface and the method mayfurther comprise forming a second opening, of a second width, to thefirst channel in the second surface. The curing, or hardening, of thebonding agent is improved by a second opening of the first channel.

The second opening may have any regular, for example circular, orirregular shape, on the second surface. In case of a non-circular shape,the second width is the greatest distance between two opposite sides ofthe second opening on the second surface of the second component. Forexample, for an elliptical opening, the second width is defined as thefull length of the major axis of this elliptical opening.

The method may further comprise the bonding agent spilling out of thesecond opening of the first channel on the second surface of the secondcomponent, thus forming a droplet of a third width, wherein the thirdwidth is greater than the second width.

The droplet may have any regular, for example circular, or irregularshape. In case of a non-circular shape, the third width is the greatestdistance between two opposite sides of the droplet on the second surfaceof the second component. The droplet may, for example, form a “mushroomhead”. Therefore, if there were a force directed from the second openingof the first channel to the first opening of the first channel, along alongitudinal direction of the first channel, the droplet would generatea mechanical resistance against this force. Hence, the droplet providesa mechanical adhesion between the first component and the secondcomponent. For an improved level of mechanical adhesion, it ispreferable for the third width to be at least 20% larger than the secondwidth, more preferably the third width is at least 40% larger than thesecond width.

The first channel may have a fourth width inside the second component;wherein the fourth width may be greater than the first width, and/orwherein the fourth width may be greater than the second width; orwherein the fourth width may be equal to the second width and to thefirst width. It is to be understood that the statements made hereinconcerning the geometric shape and determination of the first widthapply analogously to the second, third, and fourth width. When a widthis determined inside the channel, the width can be measured at anyangular orientation in a cross-sectional plane within the channel,wherein the cross-sectional plane is preferably perpendicular to alongitudinal direction of the channel. The cross-section of the channelmay be circular, elliptical, rectangular, or may have any other geometryincluding an irregular geometry.

In other words, the fourth width may be greater than the first width, orthe fourth width may be greater than the second width, or the fourthwidth may be greater than the first and the second width. If the fourthwidth is greater than the first width, there will be a mechanicalresistance preventing the bonding agent from sliding towards the firstopening of the first width under the influence of force towards thefirst opening, thereby improving the strength of the bond between thefirst component and the second component. If the fourth width is greaterthan the second width, there will be a mechanical resistance preventingthe bonding agent from sliding towards the second opening of the secondwidth under the influence of force towards the second opening, therebyimproving the strength of the bond between the first component and thesecond component. If the fourth width is greater than the first andsecond width, there will be a mechanical resistance preventing thebonding agent from sliding towards the first opening of the first widthand the second opening of the second width under the influence of aforce, thereby improving the strength of the bond between the firstcomponent and the second component.

Alternatively, the fourth width may be equal to the second width and thefirst width. This arrangement allows for the best flow of the liquidbonding agent into the first channel and possibly through the firstchannel. This arrangement may therefore be particularly suitable for asecond component for which a long first channel is required.

At least one of the first, second, third, or fourth width may be between0.3 mm and 3 mm. The inventors have found that if the first, second, or,if applicable, fourth width is too small, it is difficult to incorporatethe bonding agent into the first channel and that if the first, second,or, if applicable, fourth width is too large, the bond is not strongenough. The inventors have found that a preferred range of the first,second, or, if applicable, fourth width is therefore between 0.3 mm and3 mm, more preferably, between 0.5 mm and 2 mm. The third width isdetermined by the second width and the amount of bonding agent pushedthrough the first channel.

The first channel may be formed such that a longitudinal axis of thefirst channel is at an angle of between 80 and 110 degrees to the firstsurface and/or the second surface of the second component. The inventorshave found that in this arrangement, it is particularly easy toincorporate the bonding agent into the first channel.

In case that the first surface and/or the second surface is not flat,the angle between the longitudinal axis of the first channel is theangle between a tangential direction to the surface immediately adjacentto the first opening (in case of the first surface) or the secondopening (in case of the second surface).

The first channel may be formed such that a longitudinal axis of thefirst channel is at an angle of between 35 and 55 degrees to the firstsurface and/or the second surface of the second component. By arrangingthe first channel in this orientation, the strength of the bond can beimproved for at least two reasons.

Firstly, the length of the first channel and therefore the areaavailable for bonding can be increased, even when the maximum depth ofthe channel is limited, for example by the thickness of the secondcomponent. Here, the depth of the channel is defined as the separationmeasured at a right angle to the first surface between the deepest pointof the channel, which may be in the second opening, and the firstopening.

Secondly, for a force at a right angle to the first surface, thecomponent of the force along a longitudinal direction of the firstchannel, i.e. parallel to the wall of the first channel, that is, thecomponent that needs to overcome the sliding friction of the bondingagent in the first channel, is reduced by an angular decomposition ofthe force. For example, if there is a force F at right angles to thefirst surface pulling the bonding agent towards the first opening and ifa longitudinal axis of the first channel is at an angle of 45° to thefirst surface, the force along the longitudinal axis only amounts toapproximately 71% of F. Thus, it is harder to pull the first componentat right angles to the second component off the second component;therefore, the bond between the first component and the second componentis stronger.

The first and/or second bonding agent may be a hot melt. Handling of ahot melt releases significantly less volatile organic compounds, such assolvents, than handling of other bonding agents. Moreover, activation ofthe hot melt, by melting, can be easily timed and controlled, thussimplifying and improving the production process.

The method may further comprise the formation of a hot melt layer whichcomprises the hot melt. The hot melt layer may largely cover a bondinginterface, or bonding area, between the first component and the secondcomponent. However, it is also possible that the hot melt is onlyapplied point-wise in order to reduce the weight of the composite sportsarticle.

The method may further comprise: forming a protective layer on the firstcomponent to prevent the bonding agent from entering the firstcomponent. In order to ensure the best possible bond for a given amountof bonding agent, it is advantageous to prevent the bonding agent fromentering the first component. Therefore, it may be preferable to use aprotective layer, which may have, for example, a higher meltingtemperature than the hot melt, if hot melt is used as bonding agent.

The protective layer may comprise polyurethane, for examplethermoplastic polyurethane, to provide thermal formability. This way, astrong chemical bond may be formed between the protective layer and thebonding agent. For example, the bonding agent may also comprisethermoplastic polyurethane and the bonding agent may comprise acomposition with a lower melting temperature than the meltingtemperature of the composition of the protective layer. The bond betweenthe protective layer and the bonding agent will therefore be strong andbonding is easy to activate. Moreover, it is thus possible to reliablybond even a first component comprising very finely woven textiles to thesecond component.

Applying a bonding agent to the bonding interface may comprise applyinga sheet of solid bonding agent to the bonding interface and applyingheat and pressure to the bonding interface. For example, a suitablysized and shaped sheet of solid bonding agent may be cut by any suitablemeans, for example by a laser, and placed on either the first componentor the second component. This allows for a particularly convenienthandling. Then, at a suitable time, the bonding agent can be activatedby applying heat and the formation of the bond can be facilitated by theapplication of pressure. In particular, application of pressure alsohelps to force the bonding agent into the first channel.

Applying a sheet of solid bonding agent to the bonding location may beperformed when the shoe upper is in a flat condition. It is easier toplace a sheet of solid bonding agent to the shoe upper when it is in aflat condition. This may, for example, be performed fully automaticallyby a patch placement machine.

The method may further comprise forming a second channel in the secondcomponent. The total strength of the bond between the first componentand the second component can be increased if there is not only a firstchannel, but also a second channel. There may be a plurality ofchannels. The second channel, or each channel of the plurality ofchannels may have the properties of the first channel as describedherein.

The smallest distance between an outer edge of the first channel and anouter edge of the second channel may be between 0.3 and 3 mm. Theinventors have found that if the smallest distance between an outer edgeof the first channel and an outer edge of the second channel is toolarge, the total strength of the bond is too weak. On the other hand, ifthe smallest distance between the outer edge of the first channel and anouter edge of the second channel is too small, there is a risk of thesecond component tearing. Therefore, the smallest distance between anouter edge of the first channel and an outer edge of the second channelis preferably between 0.3 mm and 3 mm, more preferably between 0.5 mmand 2 mm.

BRIEF DESCRIPTION OF THE FIGURES

Below, exemplary embodiments of the invention will be described withreference to the figures. The Figures show:

FIGS. 1A-1B: an exemplary sports article according to the presentinvention.

FIG. 2: an exemplary midsole for an article of footwear according to thepresent invention.

FIG. 3: another exemplary midsole for an article of footwear accordingto the present invention.

FIGS. 4A-4C: exemplary cross-sectional views of a second componentaccording to the present invention.

FIG. 5: an exemplary schematic of an arrangement of a first component, aprotective layer, a bonding agent, and a second component according tothe present invention.

FIG. 6: an exemplary top view of a second component comprising aplurality of channels according to the present invention.

FIG. 7: an exemplary shoe comprising a midsole and an upper according tothe present invention.

FIGS. 8A-8B: an exemplary sports article, wherein the bond between thefirst component and the second component is directly form-fitted.

FIG. 9: a shoe with an upper, bonding agent and sole in cross section.

FIG. 10: a sole with form-fitting elements provided as elongated bars intop view.

FIG. 11: a sole with form-fitting elements provided as punctiformprotrusions in top view.

FIGS. 12-17: embodiments for form-fitting elements provided on thetopside of the sole in section.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Only some possible embodiments of the invention are described in detailbelow. It is to be understood that these exemplary embodiments can bemodified in a number of ways and combined with each other whenevercompatible and that certain features may be omitted in so far as theyappear dispensable. While the invention is described primarily withreference to a shoe, it is to be understood that the teachings of thepresent invention apply to any sports article, such as footwear,apparel, or sports accessories.

FIGS. 1A and 1B show a portion of an exemplary composite sports article(10) comprising: a first component (11); a second component (12), whichwas produced by means of an additive manufacturing technique; whereinthe first component (11) and the second component (12) are bonded toeach other by a first bonding agent and wherein there is a form-fittedbond between the first bonding agent (13) and the second component. Inother words, the bond between the first component and the secondcomponent is only indirectly form-fitted via the bonding agent (13).

The composite sports article 10 in accordance with the inventioncomprises a strong bond between the first component 11 and the secondcomponent 12, even if the bonding agent 13 does not adhere strongly tothe second component.

In the second component 12, a first 14 a, second 14 b, third and fourthform-fitting element are provided. The second component 12 may compriseany desired number of form-fitting elements.

In this example, the composite sports article 10 is a shoe, the firstcomponent 11 is a part of a shoe upper and the second component 12 is apart of a sole. In particular, the first component 11 is a bottom sideof a shoe upper and the second component 12 is a topside of the sole.

The first form-fitting element 14 a is provided on the topside of thesole 12. The first form-fitting element 14 a is provided on a midsole ofa multi-layered sole such that it faces the shoe upper.

The first 14 a and/or the second 14 b form-fitting element is providedas a channel-shaped indentation. A first channel 14 b with a firstopening, of a first width, is located in a first surface 15 of thesecond component, wherein the first channel 14 a is at least partiallyfilled with the first bonding agent 13. The first component 11 is bondedto the second component at a bonding interface, which is locatedadjacent to the first surface 15 of the second component 12 and thebonding interface comprises the first bonding agent 13.

Due to the first channel 14 a that is at least partially filled with thebonding agent 13, the bond is particularly resilient against lateralforces, such as shear forces. Lateral forces are forces that aresubstantially at a 90 degree angle to a longitudinal direction of thefirst channel 14 a. Since the total area available for a chemical bondis increased due to the presence of the first channel 14 a, the bond isalso improved against forces along a longitudinal direction of the firstchannel 14 a.

In this example, the second component 12 moreover comprises a secondchannel 14 b. The total strength of the bond between the first component11 and the second component 12 can be increased if there is not only afirst channel 14 a, but also a second channel 14 b. In this example,there is a plurality of channels. In this example, each channel of theplurality of channels has the properties of the first channel 14 a.Hereinafter, reference number 14 will generally refer to one of thechannels 14 a, 14 b.

In this example, the smallest distance between an outer edge of thefirst channel 14 and an outer edge of the second channel is between 0.3and 3 mm. The inventors have found that if the smallest distance betweenan outer edge of the first channel 14 and an outer edge of the secondchannel is too large, the total strength of the bond is too weak. On theother hand, if the smallest distance between the outer edge of the firstchannel 14 and an outer edge of the second channel is too small, thereis a risk of the second component 12 tearing itself. Therefore, thesmallest distance between an outer edge of the first channel 14 and anouter edge of the second channel is preferably between 0.3 mm and 3 mm,more preferably between 0.5 mm and 2 mm.

In this example, producing the second component 12 comprises: providinga photopolymer and selectively activating the photopolymer in order toform the second component 12. Thus, the second component 12 comprises anactivated photopolymer. Here, a photopolymer is any substance that canbe activated, i.e. cured, by light, wherein activation causes a liquidphotopolymer to solidify. A UV-curable resin is an example of aphotopolymer. UV is an abbreviation for ultraviolet. In this example,the second component 12 comprises a mixture of UV-curable resin andpolyurethane. After curing, this mixture yields a stiff and durablesecond component.

In this example, the second component 12 is constructed bystereolithography which allows for the second component 12 to be builtwith a particularly high resolution at fast production speeds.Production of the second component 12 comprises projecting ofultraviolet light through an oxygen-permeable window into a reservoir ofphotopolymer. A sequence of UV images are projected onto thephotopolymer thus selectively solidifying the photopolymer. Thepartially-constructed second component is lifted out of the photopolymerreservoir by a build platform. Oxygen may be supplied through theoxygen-permeable window, in order to prevent an undesired activation ofthe photopolymer in a region around the oxygen-permeable window, theso-called “dead zone”. This allows for a sufficient supply ofnon-activated photopolymer and prevents the partially-constructed secondcomponent from sticking to the window.

In this example, in addition to activation by light, the photopolymer ishardened additionally by heating the second component 12 with hot air,conductive heating (heat pressing), infrared radiation, or by any othersuitable method. This additional hardening greatly increases thestrength of the second component 12. In this example, the Young'smodulus of the second component 12 increases due to the additionalhardening by a factor of 10 or more. In this example, this additionalhardening is performed before bonding the second component 12 to thefirst component 11 in order to prevent damage to the second component 12during the bonding operation. Hardening at ambient temperature is alsopossible in principle, however, this would occupy more time.

In this example, the second component 12 comprises a second surface 16,wherein the second surface 16 comprises a second opening, of a secondwidth 19, to the first channel 14. The curing, or hardening, of thebonding agent 13 is improved by a second opening to the first channel14.

In this example, the bonding agent 13 spills out of the second openingof the first channel 14 on the second surface 16 of the second component12 thus forming a droplet 17 of a third width 20, wherein the thirdwidth 20 is greater than the second width 19. The droplet 17 may haveany regular, for example circular, or irregular shape. In case ofnon-circular shape, the third width 20 is the greatest distance betweentwo opposite sides of the droplet 17 on the second surface 16 of thesecond component 12. In this example, the droplet 17 forms a “mushroomhead”.

If there is a force directed from the second opening of the firstchannel 14 to the first opening of the first channel 14, along alongitudinal direction of the first channel 14, the droplet 17 providesa mechanical resistance against this force. Hence, the droplet 17provides a mechanical adhesion of the first component 11 and the secondcomponent 12. For an improved level of mechanical adhesion, it ispreferable for the third width 20 to be at least 20% larger than thesecond width 19, more preferably the third width 20 is at least 40%larger than the second width 19.

In this example, the second width is equal to the first width. Thisarrangement allows for the best flow of liquid bonding agent into thefirst channel and through the first channel. This arrangement istherefore particularly suitable for a second component for which a longfirst channel is required.

In this example, at least one of the first, second, or third width isbetween 0.3 mm and 3 mm. The inventors have found that if the first,second, or, if applicable, fourth width is too small, it is difficult toincorporate the bonding agent 13 into the first channel 14 and if thefirst, second, or, if applicable, fourth width is too large, the bond isnot strong enough. The inventors have found that a preferred range ofthe first or second width is therefore between 0.3 mm and 3 mm, morepreferably, between 0.5 mm and 2 mm. The third width 20 is determined bythe second width 19 and the amount of bonding agent 13 pushed throughthe first channel 14.

In this example, a longitudinal axis of the first channel 14 is at anangle of between 80 and 110 degrees to the first surface and/or to thesecond surface 16 of the second component 12. The inventors have found,that in this arrangement, it is particularly easy to incorporate thebonding agent 13 into the first channel 14.

In this example, the bonding agent 13 is a hot melt. Handling of a hotmelt releases significantly less volatile organic compounds, such assolvents, than handling of other bonding agents. Moreover, activation ofthe hot melt, by melting, can be easily timed and controlled, thussimplifying and improving the production process.

FIG. 2 shows an exemplary second component 12 for a sports articleaccording to the invention. The second component 12 comprises aplurality of channels 14. In this example, the second component 12 is amidsole 12 for a shoe. The present invention is greatly beneficial for ashoe, which needs to be strong and durable as it is exposed to the wholeweight of the athlete. A shoe is subject to high forces and torquesduring physical activity. A weak bond between the upper and the midsolemay increase the risk of the upper tearing off the midsole duringphysical activity. The shoe also needs to provide the right level ofsupport, for example around the ankle, yet it has to be flexible, forexample in the instep region and provide the right level of cushioning,for example in the heel region. Therefore, the shoe is advantageouslyformed as a composite article. A midsole 12 formed at least partly bymeans of an additive manufacturing technique allows for the right levelof cushioning for each part of the foot and may be customizedindividually for an athlete. For example, the heel region 22 may beengineered to provide a high level of cushioning while the toe region 23may be engineered to be firmer than the heel region. The presentinvention therefore provides a composite shoe with a preferred level offit and ideal functional properties that is at the same time durable dueto the strong bond between the shoe upper and the midsole 12.

In this example, the second component 12 is the entire midsole. Thisway, the number of components is kept as low as possible, thereforeimproving the durability and comfort of the shoe as well as simplifyingits construction.

In this example, the bonding interface is located in a rim portion 21 ofthe midsole 12. It is advantageous for the bonding interface to belocated in a rim portion 21 of the midsole, as this allows for the upperto be bonded to the midsole 12 all the way around the midsole 12,creating a strong bond, yet it is not necessary to bond the upper to themidsole at the center of the midsole, i.e. outside of the rim portion21. This reduces the amount of bonding agent 13 required, thereforereducing the weight of the shoe.

FIG. 3 shows an exemplary second component 12 according to theinvention. The second component 12 comprises a plurality of channels 14.The second component 12 is a midsole 12 for a shoe. The bondinginterface is located in a rim portion 21 of the midsole 12.

In this example, the midsole 12 comprises a lattice structure comprisinga plurality of voids 31. The voids 31 are connected to one another toform one large void within a mesh-like structure. However, the voids 31may also not be connected to one another. A lattice structure ispreferable for a plurality of applications as it allows for a strong,yet flexible and cushioning structure to be produced at low weight.Moreover, a lattice structure offers good breathability.

The properties of the lattice can be engineered to be anisotropic, forexample the lattice may stretch easily in one direction and less easilyin another direction. Additionally, the lattice may be engineered to bedenser in a first part, for example the toe region 23 of FIG. 2, of themidsole 12 and in a second part, for example the heel region 22 of FIG.2, of the midsole 12, therefore providing a firm first part and asofter, more cushioning second part.

FIGS. 4A-C show exemplary cross sections of various second components 12for a sports article according to the present invention.

FIG. 4A shows an exemplary second component 12. The second component 12is produced by means of an additive manufacturing technique andcomprises a plurality of channels 14 with a first opening, of a firstwidth 18, in a first surface 15 of the second component 12. It is to benoted that while the cross-section shown in FIG. 4A shows apparentlyseparate pieces of the second component 12, this is due to the cut shownin FIG. 4A and the apparently separate pieces are connected to oneanother at a different level of depth in the second component 12 (notshown).

The second component 12 comprises a second surface 16, wherein thesecond surface 16 comprises a second opening, of a second width 19, tothe first channel. The curing, or hardening, of the bonding agent isimproved by a second opening to the channels 14.

The first channel 14 has a fourth width 41 inside the second component12, wherein the fourth width 41 is greater than the first width 18 andwherein the fourth width is equal to the second width 19. As the fourthwidth 41 is greater than the first width 18, there will be a mechanicalresistance preventing the bonding agent 13 from sliding towards thefirst opening of the first width 18 under the influence of a force.

FIG. 4B shows an exemplary second component 12 for a sports articleaccording to the present invention. In this example, the fourth width 41is greater than the first width 18 and the second width 19. As thefourth width 41 is greater than the first width 18 and the second width19, there will be a mechanical resistance preventing the bonding agent13 from sliding towards the first opening of the first width 18 and thesecond opening of the second width 19 under the influence of a forcetowards the first opening or the second opening under the influence of aforce, thereby improving the strength of the bond between the firstcomponent and the second component 12.

FIG. 4C shows an exemplary second component 12 for a sports articleaccording to the present invention. In this example, a longitudinal axisof the first channel 14 is at an angle α 42 of between 35 and 55 degreesto the first surface 15 and to the second surface 16 of the secondcomponent 12. By arranging the first channel 14 in this orientation, thestrength of the bond can be improved for at least two reasons.

Firstly, the length of the first channel 14 and therefore the areaavailable for bonding can be increased, even when the maximum depth 43of the channel is limited, for example by the thickness 43 of the secondcomponent 12. Here the depth of the channel is defined as the separationmeasured at a right angle to the first surface between the deepest pointof the channel, which may be in the second opening, and the firstopening.

Secondly, for a force at a right angle to the first surface, thecomponent of the force along a longitudinal direction of the firstchannel 14, i.e. parallel to the wall of the first channel 14, that is,the component that needs to overcome the sliding friction of the bondingagent 13 in the first channel 14, is reduced by an angular decompositionof the force. For example, if there is a force F at right angles to thefirst surface pulling the bonding agent towards the first opening and ifa longitudinal axis of the first channel 14 is at an angle 42 of α=45degrees to the first surface, the force along the longitudinal axis onlyamounts to approximately 71% of F. Thus, it is harder to pull the firstcomponent 11 at right angles to the second component 12 off the secondcomponent 12; therefore, the bond between the first component 11 and thesecond component 12 is stronger.

In case that the first surface 15 and/or the second surface 16 is notflat, the angle between the longitudinal axis of the first channel 14 isthe angle between a tangential direction to the surface immediatelyadjacent to the first opening (in case of the first surface 15) or thesecond opening (in case of the second surface 16).

FIG. 5 shows an exemplary schematic of the arrangement of the firstcomponent 11, a second component 12, a bonding agent 13, and aprotective layer 51 for a sports article according to the presentinvention.

In this example, the first component 11 further comprises a protectivelayer 51 to prevent the bonding agent 13 from entering the firstcomponent 11. In order to ensure the best possible bond for a givenamount of bonding agent 13, it is advantageous to prevent the bondingagent 13 from entering the first component 11. A protective layer 51 isused for this purpose, which has a higher melting temperature than thehot melt, used as the bonding agent 13.

In this example, the protective layer 51 comprises polyurethane. Thisway, a strong chemical bond may be formed between the protective layer51 and the bonding agent 13. The bonding agent 13 in this example alsocomprises polyurethane. The bonding agent 13 also comprises acomposition with a lower melting temperature than the meltingtemperature of the composition of the protective layer 51. The bondbetween the protective layer and the bonding agent 13 will therefore bestrong and bonding is easy to activate. Moreover, it is thus possible toreliably bond even a first component 11 comprising very finely woventextiles to the second component 12.

FIG. 6 shows a top view of a second component 12 for a sports articleaccording to the present invention.

In this example, the second component 12 comprises a first channel 14 a,a second channel 14 b, a third channel 14 c, and a fourth channel 14 d.In this example, the smallest distance 61 between an outer edge of thefirst channel 14 a and an outer edge of the second channel 14 b isbetween 0.3 and 3 mm. The smallest distance 62 between an outer edge ofthe first channel 14 a and an outer edge of the third channel 14 c isbetween 0.3 and 3 mm. The inventors have found, that if the smallestdistance between the adjacent channels is too large, the total strengthof the bond is too weak. However, if the smallest distance betweenadjacent channels is too small, there is a risk of the second component12 tearing itself. Therefore, the smallest distance between adjacentchannels is preferably between 0.3 mm and 3 mm, more preferably between0.5 mm and 2 mm.

In this example, the first openings of the channels 14 have a circularshape on the first surface.

FIG. 7 shows an exemplary shoe 10 according to the present invention.The shoe comprises an upper 11 and a midsole 12, which was formed bymeans of an additive manufacturing technique and bonded to the upper 11according to the present invention. The shoe 10 further comprises anoutsole 71 that is adhesively attached to the midsole 12. However, theoutsole 71 may also be attached to the midsole 12 by a method accordingto the claims of the present invention. In particular, the midsole 12can comprise a second form-fitting element which faces an outsole 71 ofthe multi-layered sole and which is bonded to the outsole 71 via asecond bonding agent or in direct engagement in a form-fitted manner.Hence, it is possible to also provide a directly or indirectlyform-fitted bond between the outsole 71 and the midsole 12 to improvethe resilience of the bond between the outsole 71 and the midsole 12particularly against lateral forces, such as shear forces.

In this example, the midsole 12 comprises a lattice structure comprisinga plurality of voids 31. The voids 31 may be connected to one another toform one large void 31 within a mesh-like structure, or the voids 31 maynot be connected to one another. A lattice structure is preferable for aplurality of applications as it allows for a strong, yet flexible andcushioning structure to be produced at low weight. Moreover, a latticestructure offers good breathability.

In this example, the shoe upper 11 is a textile shoe upper. Inparticular, the shoe upper 11 is weft-knitted and/or warp-knitted. Thus,the shoe upper 11 is particularly flexible and comfortable to wear.

FIGS. 8A and 8B show an example of a first component 11 and a secondcomponent 12, wherein the bond between the first component 11 and thesecond component 12 is directly form-fitted. However, the bond stillalso uses a first bonding agent 13, for example to generate a basicadhesion to hold the first 11 and the second 12 component in theform-fitted bond.

In FIG. 8A, one first form-fitting element is provided in the secondcomponent 12. The first form-fitting element is provided as a surfacingbar. FIG. 8B shows an example in which the first form-fitting element isprovided as a channel-shaped indentation. In this case, thechannel-shaped indentation is provided such that a channel extends alonga surface of the second component 12, for example as a groove in asurface of the second component 12.

FIGS. 9-17 show further embodiments of the present invention.

Example 1

Shoe (10), comprising a textile upper (11) and a sole (12),characterized in that a bottom side of the upper (11) and a topside ofthe sole (12) are bonded to each other in a form-fitted manner via a hotmelt layer (13).

Example 2

Shoe according to example 1, characterized in that form-fitting elements(91) are provided at least on the topside of the sole (12).

Example 3

Shoe according to example 1 or 2, characterized in that the form-fittingelements (91) facing the shoe upper (11) are provided on a midsole (91)of a multi-layered sole (12).

Example 4

Shoe according to example 3, characterized in that the midsole (91)comprises form-fitting elements (91), which face an outsole (71) of themulti-layered sole (12) and are bonded to the outsole (71) via a hotmelt layer (13) or in direct engagement in a form-fitted manner.

Example 5

Shoe according to example 2, characterized in that the form-fittingelements (91) are provided as punctiform indentations and/or aspunctiform protrusions.

Example 6

Shoe according to example 2, characterized in that the form-fittingelements (91) are provided as channel-shaped indentations and/or assurfacing bars.

Example 7

Shoe according to one of the above examples 1-6, characterized in thatthe sole (12), in particular the upper region of the sole (12) or amidsole (91) is additively manufactured forming undercut form-fittingelements (91).

Example 8

Method for manufacturing a shoe (10), comprising the following methodsteps:

-   -   producing a textile upper (11) of the shoe (10);    -   producing a sole (12) of the shoe (10), wherein form-fitting        elements (91) are provided on the topside of the sole (12);    -   bonding the topside of the sole (12) and the bottom side of the        upper (11) to each other by a hot melt layer (13).

Example 9

Method according to example 8, characterized in that during the bondingof the topside of the sole (12) to the bottom side of the upper (11),preferably under application of heat, a pressure is applied to thebonding area between the sole (12) and the upper (11).

Example 10

Method according to one of the examples 8 or 9, characterized in thatthe production of the sole (12), in particular of an upper region of thesole (12) or a midsole (91), is carried out by means of an additivemanufacturing method.

Example 11

Shoe (10), comprising an upper (11) and a sole (12), characterized inthat a bottom side of the upper (11) and a topside of the sole (12) arebonded to each other by a hot melt layer (13), wherein there is aform-fitted bond between the hot melt layer (13) and at least thetopside of the sole (12).

Example 12

Shoe according to example 11, characterized in that form-fittingelements (91) are provided at least on the topside of the sole (12).

Example 13

Shoe according to example 12, characterized in that the form-fittingelements (91) are provided as punctiform indentations and/or aspunctiform protrusions.

Example 14

Shoe according to example 12, characterized in that the form-fittingelements (91) are provided as channel-shaped indentations and/or assurfacing bars.

Example 15

Shoe according to one of the above examples 11-14, characterized in thatthe sole (12), in particular an upper region of the sole (12) or amidsole (92) is additively manufactured forming undercut form-fittingelements (91).

Example 16

Shoe according to one of the above examples 11-15, characterized in thatthere is an additional form-fitted bond between the hot melt layer (13)and the bottom side of the upper (11).

Example 17

Method for manufacturing a shoe (10), comprising the following methodsteps:

-   -   producing an upper (11) of the shoe (10);    -   producing a sole (12) of the shoe (10), wherein form-fitting        elements (91) are provided on the topside of the sole (12);    -   bonding the topside of the sole (12) and the bottom side of the        upper (11) to each other by a hot melt layer (13) such that the        hot melt layer (13) forms a form-fitted bond with the topside of        the sole (12).

Example 18

Method according to example 17, characterized in that during the bondingof the topside of the sole (12) to the bottom side of the upper (11),preferably under application of heat, a pressure is applied to thebonding area between the sole (12) and the upper (11).

Example 19

Method according to one of the examples 17 or 18, characterized in thatthe production of the sole (12), in particular of an upper region of thesole (12) or a midsole (92), is carried out by means of an additivemanufacturing method.

Example 20

Method according to one of the above examples 17 through 19,characterized in that in addition to the formation of the form-fittedbond between the topside of the sole (12) and the hot melt layer (13), aform-fitted bond is formed between the bottom side of the upper (11) andthe hot melt layer (13).

Below, examples 1-20 will be described in further detail with referenceto FIGS. 9-17.

The shoe 10 outlined in FIG. 9 comprises an upper 11 and a sole 12.Between the upper 11 and the sole 12, there is a hot melt layer 13(shown in the Figures by points) providing a form-fitted bond betweenthe bottom side of the upper 11 and the topside of the sole 12. The sole12, in turn, has two layers in this example according to the invention,wherein a midsole 92 contacts the hot melt layer 13 and an outsole 71joins below the midsole 92.

The upper 11 of the shoe 10 is essentially manufactured from a textilefabric and serves the purpose of accommodating the foot of the user. Thesole 12, which is for example formed from a polyurethane material,contacts the ground during walking/running with the bottom side of theoutsole 71.

Form-fitting elements 91 are provided on the topside of the midsole92—and thus also on the topside of the multi-layered sole 12—in theembodiment of the shoe 10 shown in FIG. 1. For reasons of clarity,merely one form-fitting element 91 has a reference number. Theform-fitting elements 91 shown here protrude from the surface of themidsole 92 in a cam-like manner tilted towards the heel region of theshoe 10, where they are encompassed and covered by the hot melt layer13. This tilt at an acute angle to the base of the topside of the sole12 results in undercuts, which are filled by the hot melt layer 13 suchthat there is a manifold form-fitted bond between the hot melt layer 13and the topside of the sole 12.

What is not shown in the drawings is the further embodiment according towhich such geometrically modified undercut form-fitting elements 91 mayalso protrude from the opposite surface of the midsole 92. There, thesecan be enclosed by an additional hot melt layer 13 extending between theoutsole 71 and the midsole 92, or they directly engage in the uppersurface of the outsole 71 consisting of thermoplastic material.

For manufacturing the shoe 10, the upper 11 and the sole 12 are firstproduced separately and are only subsequently bonded to each other bythe hot melt layer 13. Producing the upper 11 can for example be carriedout by means of known methods of textile technology for manufacturing atextile fabric. For producing the sole 12, for practical purposes themidsole 92 is manufactured first, preferably by means of an additivemanufacturing method (layer manufacturing methods as in 3D printing).During this additive manufacturing, the form-fitting elements 91 may beprovided at least on the topside of the midsole 92. In a furthermanufacturing step, the midsole 92 may then be bonded to the outsole 71,for example directly by adhesive force or in a form-fitted manner andagain directly or via a hot melt layer 13. For bonding the upper 11 tothis sole 12, subsequently, a geometrically limited hot melt layer 13 isinserted between the upper 11 and the sole 12 and is melted under theapplication of pressure and temperature. The melted hot melt layer 13flows around the form-fitting elements 91 on the sole 12 and enters thetextile fabric of the upper 11 such that an elastic form-fitted bondbetween hot melt layer 13 and sole 12 as well as between hot melt layer13 and upper 11 is given after cooling.

The form-fitting elements 91 outlined in section in FIG. 9 do not haveto be tilted locally limited elevations from the surface of the midsole92. These can also be cuts across the longitudinal extension ofbar-shaped or strip-shaped form-fitting elements 91 with tilted flankson and/or under the midsole 92, as outlined in FIG. 10 in top view.There, linear form-fitting elements 91 run parallel to each other andacross the longitudinal extension of the shoe 10.

FIG. 11 shows an embodiment, wherein the form-fitting elements 91 areprovided in a punctiform manner. In particular, the form-fittingelements 91 are provided as knobs (protrusions), which are distributedon the topside of the midsole 92. For reasons of clarity, only three ofthe form-fitting elements 91 are provided with reference numbers in FIG.11 as well.

FIGS. 12 through 17 show preferred cross sections of the form-fittingelements 91 in a sectional plane chosen analogously to that of FIG. 9.While in elongated form-fitting elements (as shown in FIG. 10), thecross sections are constant or constantly change along the longitudinaldirection of the form-fitting elements, the punctiform form-fittingelements (as shown in FIG. 11) may be provided axisymmetrically, then,the cross sections are rotationally symmetrical.

The form-fitting elements 91 shown in FIGS. 12 through 14 arerespectively provided as a protrusion/elevation on or as an indentationin the topside of the midsole 92 and encompassed by or at leastpartially filled by the hot melt layer 13. The form-fitting element 91from FIG. 12 has a cross section in form of a parallelogram. Theform-fitting element 91 from FIG. 13 has a cross section in form of asymmetrical trapezoid and the form-fitting element 91 from FIG. 14 isprovided in a balloon-shaped or in a drop-shaped manner.

The form-fitting elements 91 shown in FIGS. 15 through 17 arerespectively recessed into the topside of the midsole 92 as indentationsand at least partially filled with hot melt from the layer 13. Theform-fitting element 91 from FIG. 15 has a cross section in form of asymmetrical trapezoid. The form-fitting element 91 from FIG. 16 has across section in form of a parallelogram and the form-fitting element 91from FIG. 17 is, in turn, provided in a balloon-shaped or in adrop-shaped manner. The form-fitting elements 91 shown in FIGS. 15through 17 are respectively entirely filled with hot melt.

However, it is also possible that the form-fitting element 91 is notentirely filled with hot melt such that, rather, a void remains. Inother words, it is, thus, not necessary that the form-fitting element 91is entirely filled with hot melt. An at least partial entering of theform-fitting element 91 by the hot melt is sufficient, wherein theentering must at least be carried out to a certain degree, such that aform-fitted bond is formed between the form-fitting element 91 and thehot melt layer 13 which is mechanically sufficiently robust.

Thus, the cross-section forms are not relevant in detail. It merely hasto be ensured that respectively at least one sufficient undercutoriented for example in parallel to the bonding level is provided at theform-fitting elements 91 such that there is a form-fitted bond betweenthese and the hot melt layer 13.

Although the embodiments on the one hand show elongated form-fittingelements 91 reaching across the topside of the sole 12 and on the otherhand show punctiform form-fitting elements 91, mixed forms, such as ovalform-fitting elements, i.e. form-fitting elements comprising anoval-shaped contour in a top view of the sole 12 (analogously to theview chosen in FIG. 11), can also be realized.

Although the sole 12 has a two-layered setup of midsole 92 and outsole71 in the shown embodiments, another setup of the sole 12 is alsoconceivable. For example, the sole 12 may consist of one layer, i.e. ofa homogeneous material layer, or of more than two layers. Irrespectiveof the specific setup of the sole 12, form-fitting elements 91 are inany case provided on the topside of the sole 12 facing the upper 11 ofthe shoe 10.

Thus, the shoe 10 has an upper 11 and a sole 12, with the bottom side ofthe upper 11 and the topside of the sole 12 being bonded to each otherin a form-fitted manner by a layer 13 of hot melt. In any case,form-fitting elements 91 are provided on the topside of the sole 12,which effect a form-fitted bond between the hot melt layer 13 and thetopside of the sole 12/its midsole 92. The latter can, moreover, bebonded to a subjacent outsole 71 via a further hot melt layer betweenthe outsole 71 and the profiled midsole 92 or by direct engagement ofthe midsole 92 in the thermoplastic outsole 71. Above these levels, thehot melt may have entered the fabric of the shoe upper 11. Theform-fitting elements 91 may be provided both as punctiform protrusionsor indentations as well as elongated channels or bars at the respectivesurface. Preferably, a multi-layered sole 12 is manufactured at leastpartly by means of an additive manufacturing method and the form-fittingelements 91 are provided as integral parts on the topside of the sole 12right in the course of this.

REFERENCE NUMBERS

-   -   10: composite sports article,    -   11: first component,    -   12: second component,    -   13: bonding agent,    -   14, 14 a, 14 b: channel,    -   15: first surface,    -   16: second surface,    -   17: droplet,    -   18: first width,    -   19: second width,    -   20: third width,    -   21: rim portion,    -   22: heel region,    -   23: toe region,    -   31: void,    -   41: fourth width,    -   42: angle,    -   43: thickness,    -   51: protective layer,    -   61, 62: smallest distance between an outer edge of a first        channel and an outer edge of an adjacent second channel,    -   71: outsole,    -   91: form-fitting element,    -   92: midsole.

What is claimed is:
 1. A composite sports article, comprising: a firstcomponent comprising a shoe upper; a second component comprising a sole,which was manufactured by means of an additive manufacturing technique,wherein the second component comprises an upper surface, an opposinglower surface, and at least one form-fitting element extending from theupper surface to the lower surface; and a heat-activated bonding agentthat bonds the first component to the second component, wherein theheat-activated bonding agent is arranged on the upper surface of thesecond component at an interface between a lower surface of the firstcomponent and the upper surface of the second component, and wherein theheat-activated bonding agent extends through the at least oneform-fitting element onto the lower surface of the second component. 2.The composite sports article according to claim 1, wherein the compositesports article is a shoe; and wherein the first component is a bottomside of the shoe upper and the second component is a topside of thesole.
 3. The composite sports article according to claim 1, wherein thesecond component comprises a lattice structure comprising a plurality ofvoids.
 4. The composite sports article according to claim 1, wherein theat least one form-fitting element is provided in a midsole of the sole.5. The composite sports article according to claim 1, wherein the atleast one form fitting element comprises a first channel with a firstopening, of a first width, which is located in the upper surface of thesecond component.
 6. The composite sports article according to claim 5,wherein the second component comprises a second surface, wherein thesecond surface comprises a second opening, of a second width, of thefirst channel.
 7. The composite sports article according to claim 6,wherein the first channel has a fourth width inside the secondcomponent; and wherein the fourth width is greater than the first width,and/or wherein the fourth width is greater than the second width; orwherein the fourth width is equal to the second width and the firstwidth.
 8. The composite sports article according to claim 1, wherein theheat-activated bonding agent comprises a layer of a hot melt.
 9. Thecomposite sports article according to claim 1, wherein the firstcomponent further comprises a protective layer to prevent theheat-activated bonding agent from entering the first component.
 10. Thecomposite sports article of claim 1, wherein the heat-activated bondingagent bonds the upper surface of the second component to a lower surfaceof the first component.
 11. A composite sports article, comprising: ashoe upper; a midsole comprising a lattice structure defining aplurality of voids, wherein the midsole is manufactured by an additivemanufacturing technique, and wherein the midsole comprises a centerportion surrounded by a rim portion, a plurality of channel-shapedindentations formed in the rim portion of the midsole, wherein nochannel-shaped indentations are arranged in the center portion; and abonding agent that bonds the shoe upper to the midsole, wherein thebonding agent is arranged at an interface between a lower surface of theshoe upper and an upper surface of the rim portion of the midsole,wherein each of the plurality of channel-shaped indentations is at leastpartially filled with the bonding agent.
 12. The composite sportsarticle of claim 1, wherein the bonding agent comprises a thermoplasticmaterial selected from thermoplastic polyurethane, a polyamide, and apolyether block amide.
 13. The composite sports article of claim 11,wherein the plurality of channel-shaped indentations are spaced from oneanother by a distance of 0.3 mm to 3 mm.
 14. The composite sportsarticle of claim 11, wherein the lattice structure comprises anactivated photopolymer.
 15. The composite sports article of claim 11,wherein the shoe upper comprises a knit material.